Epidemiologic studies have associated lung function decreases with summertime ambient air pollution described as "acid haze" which appears to be ozone (O3) combined with some acidic compounds. This study proposes and investigation of "acid haze" in a controlled laboratory setting. Thus the overall objective of this project is to elucidate further the potential human toxicity of inhalation of these wide spread serious air pollutants. The specific pollutants to be studied are O3, sulfuric acid (H2SO4) and nitric acid (HNO3). The pulmonary function effects of these three pollutants will be studied in groups of adolescent subjects with allergic asthma. The exposures will be carried out for 90 minutes during intermittent exercise on two consecutive days. The investigation of the pulmonary effects of sulfur oxide pollutants also will be extended to other age groups. For instance, it is suspected that young children may be especially sensitive to inhaled irritants due to their small airway size and immature immunologic system. Therefore the effects of SO2 inhalation will be investigated in young children aged 6-10 years. The effects of H2SO4 will be studied in older asthmatic subjects over the age of 55 years, another age group which may be at risk with respect to the inhaled effects of air pollutants. Adolescent asthmatic subjects have been shown to be sensitive to low concentrations of H2SO4 whereas adult asthmatic subjects appear less sensitive. Older subjects have not been studied. In all studies the primary pulmonary functions to be assessed will be forced expiratory volume in one second (FEV1), total respiratory resistance and maximal flow. These tests will be measured before and after exposure to the test atmospheres. The adolescent subjects will inhale the test atmospheres for 90 minutes during intermittent exercise on two consecutive days. They will return on the third day for pulmonary tests to detect persistent or delayed effects of the exposure. The younger and older subjects will inhale the SO2 or H2SO4 on a single day. This research will provide important data on the health effects of air pollution which will help establish a scientific base for setting national ambient air quality standards.